How do you find the amount of time given I=$54, P=$800, r=4.5%?

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Answer 1 · 2016-12-12T01:49:14

#1 7/9# years

Words used in question indicate that when a principal amount #P#, is invested for a time of #t# years at a rate of #r#, the interest earned is #I#.

In such cases as #I=(P×r×t)/100#, we can have #t=(I×100)/(P×r)#.

As we have to calculate time #t# given #I=$64#, #P=$800# and #r=4.5%#,

#t=(64×100)/(800×4.5)#

= #(64×cancel100^1)/(cancel800^8×4.5)#

= #64/(8×4.5)#

= #64/36# (and dividing by #4#)

= #(16cancel64)/(9cancel36)#

= #16/9=1 7/9# years.